gcc/cp/cp-lang.c

   1 /* Language-dependent hooks for C++.
   2    Copyright 2001, 2002 Free Software Foundation, Inc.
   3    Contributed by Alexandre Oliva  <aoliva@redhat.com>
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "tree.h"
  27 #include "cp-tree.h"
  28 #include "c-common.h"
  29 #include "toplev.h"
  30 #include "langhooks.h"
  31 #include "langhooks-def.h"
  32
  33 static HOST_WIDE_INT cxx_get_alias_set (tree);
  34 static bool ok_to_generate_alias_set_for_type (tree);
  35 static bool cxx_warn_unused_global_decl (tree);
  36 static tree cp_expr_size (tree);
  37 static bool cp_var_mod_type_p (tree);
  38
  39 #undef LANG_HOOKS_NAME
  40 #define LANG_HOOKS_NAME "GNU C++"
  41 #undef LANG_HOOKS_INIT
  42 #define LANG_HOOKS_INIT cxx_init
  43 #undef LANG_HOOKS_FINISH
  44 #define LANG_HOOKS_FINISH cxx_finish
  45 #undef LANG_HOOKS_CLEAR_BINDING_STACK
  46 #define LANG_HOOKS_CLEAR_BINDING_STACK pop_everything
  47 #undef LANG_HOOKS_INIT_OPTIONS
  48 #define LANG_HOOKS_INIT_OPTIONS cxx_init_options
  49 #undef LANG_HOOKS_DECODE_OPTION
  50 #define LANG_HOOKS_DECODE_OPTION c_common_decode_option
  51 #undef LANG_HOOKS_POST_OPTIONS
  52 #define LANG_HOOKS_POST_OPTIONS c_common_post_options
  53 #undef LANG_HOOKS_GET_ALIAS_SET
  54 #define LANG_HOOKS_GET_ALIAS_SET cxx_get_alias_set
  55 #undef LANG_HOOKS_EXPAND_CONSTANT
  56 #define LANG_HOOKS_EXPAND_CONSTANT cplus_expand_constant
  57 #undef LANG_HOOKS_EXPAND_EXPR
  58 #define LANG_HOOKS_EXPAND_EXPR cxx_expand_expr
  59 #undef LANG_HOOKS_SAFE_FROM_P
  60 #define LANG_HOOKS_SAFE_FROM_P c_safe_from_p
  61 #undef LANG_HOOKS_PARSE_FILE
  62 #define LANG_HOOKS_PARSE_FILE c_common_parse_file
  63 #undef LANG_HOOKS_DUP_LANG_SPECIFIC_DECL
  64 #define LANG_HOOKS_DUP_LANG_SPECIFIC_DECL cxx_dup_lang_specific_decl
  65 #undef LANG_HOOKS_UNSAVE_EXPR_NOW
  66 #define LANG_HOOKS_UNSAVE_EXPR_NOW cxx_unsave_expr_now
  67 #undef LANG_HOOKS_MAYBE_BUILD_CLEANUP
  68 #define LANG_HOOKS_MAYBE_BUILD_CLEANUP cxx_maybe_build_cleanup
  69 #undef LANG_HOOKS_TRUTHVALUE_CONVERSION
  70 #define LANG_HOOKS_TRUTHVALUE_CONVERSION c_common_truthvalue_conversion
  71 #undef LANG_HOOKS_INSERT_DEFAULT_ATTRIBUTES
  72 #define LANG_HOOKS_INSERT_DEFAULT_ATTRIBUTES cxx_insert_default_attributes
  73 #undef LANG_HOOKS_UNSAFE_FOR_REEVAL
  74 #define LANG_HOOKS_UNSAFE_FOR_REEVAL c_common_unsafe_for_reeval
  75 #undef LANG_HOOKS_SET_DECL_ASSEMBLER_NAME
  76 #define LANG_HOOKS_SET_DECL_ASSEMBLER_NAME mangle_decl
  77 #undef LANG_HOOKS_MARK_ADDRESSABLE
  78 #define LANG_HOOKS_MARK_ADDRESSABLE cxx_mark_addressable
  79 #undef LANG_HOOKS_PRINT_STATISTICS
  80 #define LANG_HOOKS_PRINT_STATISTICS cxx_print_statistics
  81 #undef LANG_HOOKS_PRINT_XNODE
  82 #define LANG_HOOKS_PRINT_XNODE cxx_print_xnode
  83 #undef LANG_HOOKS_PRINT_DECL
  84 #define LANG_HOOKS_PRINT_DECL cxx_print_decl
  85 #undef LANG_HOOKS_PRINT_TYPE
  86 #define LANG_HOOKS_PRINT_TYPE cxx_print_type
  87 #undef LANG_HOOKS_PRINT_IDENTIFIER
  88 #define LANG_HOOKS_PRINT_IDENTIFIER cxx_print_identifier
  89 #undef LANG_HOOKS_DECL_PRINTABLE_NAME
  90 #define LANG_HOOKS_DECL_PRINTABLE_NAME  cxx_printable_name
  91 #undef LANG_HOOKS_PRINT_ERROR_FUNCTION
  92 #define LANG_HOOKS_PRINT_ERROR_FUNCTION cxx_print_error_function
  93 #undef LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL
  94 #define LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL cxx_warn_unused_global_decl
  95
  96 #undef LANG_HOOKS_FUNCTION_INIT
  97 #define LANG_HOOKS_FUNCTION_INIT cxx_push_function_context
  98 #undef LANG_HOOKS_FUNCTION_FINAL
  99 #define LANG_HOOKS_FUNCTION_FINAL cxx_pop_function_context
 100
 101 /* Attribute hooks.  */
 102 #undef LANG_HOOKS_COMMON_ATTRIBUTE_TABLE
 103 #define LANG_HOOKS_COMMON_ATTRIBUTE_TABLE c_common_attribute_table
 104 #undef LANG_HOOKS_FORMAT_ATTRIBUTE_TABLE
 105 #define LANG_HOOKS_FORMAT_ATTRIBUTE_TABLE c_common_format_attribute_table
 106 #undef LANG_HOOKS_ATTRIBUTE_TABLE
 107 #define LANG_HOOKS_ATTRIBUTE_TABLE cxx_attribute_table
 108
 109 #undef LANG_HOOKS_TREE_INLINING_WALK_SUBTREES
 110 #define LANG_HOOKS_TREE_INLINING_WALK_SUBTREES \
 111   cp_walk_subtrees
 112 #undef LANG_HOOKS_TREE_INLINING_CANNOT_INLINE_TREE_FN
 113 #define LANG_HOOKS_TREE_INLINING_CANNOT_INLINE_TREE_FN \
 114   cp_cannot_inline_tree_fn
 115 #undef LANG_HOOKS_TREE_INLINING_ADD_PENDING_FN_DECLS
 116 #define LANG_HOOKS_TREE_INLINING_ADD_PENDING_FN_DECLS \
 117   cp_add_pending_fn_decls
 118 #undef LANG_HOOKS_TREE_INLINING_TREE_CHAIN_MATTERS_P
 119 #define LANG_HOOKS_TREE_INLINING_TREE_CHAIN_MATTERS_P \
 120   cp_is_overload_p
 121 #undef LANG_HOOKS_TREE_INLINING_AUTO_VAR_IN_FN_P
 122 #define LANG_HOOKS_TREE_INLINING_AUTO_VAR_IN_FN_P \
 123   cp_auto_var_in_fn_p
 124 #undef LANG_HOOKS_TREE_INLINING_COPY_RES_DECL_FOR_INLINING
 125 #define LANG_HOOKS_TREE_INLINING_COPY_RES_DECL_FOR_INLINING \
 126   cp_copy_res_decl_for_inlining
 127 #undef LANG_HOOKS_TREE_INLINING_ANON_AGGR_TYPE_P
 128 #define LANG_HOOKS_TREE_INLINING_ANON_AGGR_TYPE_P anon_aggr_type_p
 129 #undef LANG_HOOKS_TREE_INLINING_VAR_MOD_TYPE_P
 130 #define LANG_HOOKS_TREE_INLINING_VAR_MOD_TYPE_P cp_var_mod_type_p
 131 #undef LANG_HOOKS_TREE_INLINING_START_INLINING
 132 #define LANG_HOOKS_TREE_INLINING_START_INLINING cp_start_inlining
 133 #undef LANG_HOOKS_TREE_INLINING_END_INLINING
 134 #define LANG_HOOKS_TREE_INLINING_END_INLINING cp_end_inlining
 135 #undef LANG_HOOKS_TREE_DUMP_DUMP_TREE_FN
 136 #define LANG_HOOKS_TREE_DUMP_DUMP_TREE_FN cp_dump_tree
 137 #undef LANG_HOOKS_TREE_DUMP_TYPE_QUALS_FN
 138 #define LANG_HOOKS_TREE_DUMP_TYPE_QUALS_FN cp_type_quals
 139 #undef LANG_HOOKS_EXPR_SIZE
 140 #define LANG_HOOKS_EXPR_SIZE cp_expr_size
 141
 142 #undef LANG_HOOKS_MAKE_TYPE
 143 #define LANG_HOOKS_MAKE_TYPE cxx_make_type
 144 #undef LANG_HOOKS_TYPE_FOR_MODE
 145 #define LANG_HOOKS_TYPE_FOR_MODE c_common_type_for_mode
 146 #undef LANG_HOOKS_TYPE_FOR_SIZE
 147 #define LANG_HOOKS_TYPE_FOR_SIZE c_common_type_for_size
 148 #undef LANG_HOOKS_SIGNED_TYPE
 149 #define LANG_HOOKS_SIGNED_TYPE c_common_signed_type
 150 #undef LANG_HOOKS_UNSIGNED_TYPE
 151 #define LANG_HOOKS_UNSIGNED_TYPE c_common_unsigned_type
 152 #undef LANG_HOOKS_SIGNED_OR_UNSIGNED_TYPE
 153 #define LANG_HOOKS_SIGNED_OR_UNSIGNED_TYPE c_common_signed_or_unsigned_type
 154 #undef LANG_HOOKS_INCOMPLETE_TYPE_ERROR
 155 #define LANG_HOOKS_INCOMPLETE_TYPE_ERROR cxx_incomplete_type_error
 156 #undef LANG_HOOKS_TYPE_PROMOTES_TO
 157 #define LANG_HOOKS_TYPE_PROMOTES_TO cxx_type_promotes_to
 158
 159 /* Each front end provides its own hooks, for toplev.c.  */
 160 const struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;
 161
 162 /* Tree code classes.  */
 163
 164 #define DEFTREECODE(SYM, NAME, TYPE, LENGTH) TYPE,
 165
 166 const char tree_code_type[] = {
 167 #include "tree.def"
 168   'x',
 169 #include "c-common.def"
 170   'x',
 171 #include "cp-tree.def"
 172 };
 173 #undef DEFTREECODE
 174
 175 /* Table indexed by tree code giving number of expression
 176    operands beyond the fixed part of the node structure.
 177    Not used for types or decls.  */
 178
 179 #define DEFTREECODE(SYM, NAME, TYPE, LENGTH) LENGTH,
 180
 181 const unsigned char tree_code_length[] = {
 182 #include "tree.def"
 183   0,
 184 #include "c-common.def"
 185   0,
 186 #include "cp-tree.def"
 187 };
 188 #undef DEFTREECODE
 189
 190 /* Names of tree components.
 191    Used for printing out the tree and error messages.  */
 192 #define DEFTREECODE(SYM, NAME, TYPE, LEN) NAME,
 193
 194 const char *const tree_code_name[] = {
 195 #include "tree.def"
 196   "@@dummy",
 197 #include "c-common.def"
 198   "@@dummy",
 199 #include "cp-tree.def"
 200 };
 201 #undef DEFTREECODE
 202
 203 /* Check if a C++ type is safe for aliasing.
 204    Return TRUE if T safe for aliasing FALSE otherwise.  */
 205
 206 static bool
 207 ok_to_generate_alias_set_for_type (tree t)
 208 {
 209   if (TYPE_PTRMEMFUNC_P (t))
 210     return true;
 211   if (AGGREGATE_TYPE_P (t))
 212     {
 213       if ((TREE_CODE (t) == RECORD_TYPE) || (TREE_CODE (t) == UNION_TYPE))
 214         {
 215           tree fields;
 216           /* Backend-created structs are safe.  */
 217           if (! CLASS_TYPE_P (t))
 218             return true;
 219           /* PODs are safe.  */
 220           if (! CLASSTYPE_NON_POD_P(t))
 221             return true;
 222           /* Classes with virtual baseclasses are not.  */
 223           if (TYPE_USES_VIRTUAL_BASECLASSES (t))
 224             return false;
 225           /* Recursively check the base classes.  */
 226           if (TYPE_BINFO (t) != NULL && TYPE_BINFO_BASETYPES (t) != NULL)
 227             {
 228               int i;
 229               for (i = 0; i < TREE_VEC_LENGTH (TYPE_BINFO_BASETYPES (t)); i++)
 230                 {
 231                   tree binfo = TREE_VEC_ELT (TYPE_BINFO_BASETYPES (t), i);
 232                   if (!ok_to_generate_alias_set_for_type (BINFO_TYPE (binfo)))
 233                     return false;
 234                 }
 235             }
 236           /* Check all the fields.  */
 237           for (fields = TYPE_FIELDS (t); fields; fields = TREE_CHAIN (fields))
 238             {
 239               if (TREE_CODE (fields) != FIELD_DECL)
 240                 continue;
 241               if (! ok_to_generate_alias_set_for_type (TREE_TYPE (fields)))
 242                 return false;
 243             }
 244           return true;
 245         }
 246       else if (TREE_CODE (t) == ARRAY_TYPE)
 247         return ok_to_generate_alias_set_for_type (TREE_TYPE (t));
 248       else
 249         /* This should never happen, we dealt with all the aggregate
 250            types that can appear in C++ above.  */
 251         abort ();
 252     }
 253   else
 254     return true;
 255 }
 256
 257 /* Special routine to get the alias set for C++.  */
 258
 259 static HOST_WIDE_INT
 260 cxx_get_alias_set (tree t)
 261 {
 262   /* It's not yet safe to use alias sets for classes in C++.  */
 263   if (!ok_to_generate_alias_set_for_type(t))
 264     return 0;
 265
 266   return c_common_get_alias_set (t);
 267 }
 268
 269 /* Called from check_global_declarations.  */
 270
 271 static bool
 272 cxx_warn_unused_global_decl (tree decl)
 273 {
 274   if (TREE_CODE (decl) == FUNCTION_DECL && DECL_DECLARED_INLINE_P (decl))
 275     return false;
 276   if (DECL_IN_SYSTEM_HEADER (decl))
 277     return false;
 278
 279   /* Const variables take the place of #defines in C++.  */
 280   if (TREE_CODE (decl) == VAR_DECL && TREE_READONLY (decl))
 281     return false;
 282
 283   return true;
 284 }
 285
 286 /* Langhook for expr_size: Tell the backend that the value of an expression
 287    of non-POD class type does not include any tail padding; a derived class
 288    might have allocated something there.  */
 289
 290 static tree
 291 cp_expr_size (tree exp)
 292 {
 293   if (CLASS_TYPE_P (TREE_TYPE (exp)))
 294     {
 295       /* The backend should not be interested in the size of an expression
 296          of a type with both of these set; all copies of such types must go
 297          through a constructor or assignment op.  */
 298       if (TYPE_HAS_COMPLEX_INIT_REF (TREE_TYPE (exp))
 299           && TYPE_HAS_COMPLEX_ASSIGN_REF (TREE_TYPE (exp))
 300           /* But storing a CONSTRUCTOR isn't a copy.  */
 301           && TREE_CODE (exp) != CONSTRUCTOR)
 302         abort ();
 303       /* This would be wrong for a type with virtual bases, but they are
 304          caught by the abort above.  */
 305       return CLASSTYPE_SIZE_UNIT (TREE_TYPE (exp));
 306     }
 307   else
 308     /* Use the default code.  */
 309     return lhd_expr_size (exp);
 310 }
 311
 312 /* Returns true if T is a variably modified type, in the sense of C99.
 313    This routine needs only check cases that cannot be handled by the
 314    language-independent logic in tree-inline.c.  */
 315
 316 static bool
 317 cp_var_mod_type_p (tree type)
 318 {
 319   /* If TYPE is a pointer-to-member, it is variably modified if either
 320      the class or the member are variably modified.  */
 321   if (TYPE_PTRMEM_P (type) || TYPE_PTRMEMFUNC_P (type))
 322     return (variably_modified_type_p (TYPE_PTRMEM_CLASS_TYPE (type))
 323             || variably_modified_type_p (TYPE_PTRMEM_POINTED_TO_TYPE (type)));
 324
 325   /* All other types are not variably modified.  */
 326   return false;
 327 }
 328